1. Field of the Invention
This invention relates generally to segmented storage logging and controlling and more particularly to a system and method for the efficient maintenance of segments and segment portions of a segmented serial storage device for the reading and writing of text pages thereon.
2. Description of the Prior Art
Described in U.S. Pat. Nos. 3,753,239 and 3,781,813 is a technique for logging the utilization of storage blocks on a serial bulk memory and assigning blocks for the storage of new and revised text pages to eliminate the burden to a text processing system operator of having to keep track of the logical sequence of storage blocks that correspond to pages of a document being prepared or revised. The log was recorded onto a block at the beginning of the memory at the completion of each storage or deletion operation.
The above-referenced patents fail to address the possibility in which a page is recalled for storage in the text processing system when sufficient memory capacity does not exist in the system for storage of the entire page. In such a situation, it would be very advantageous to the operator to be able to recall that portion of the page that could be accommodated by the text processing system memory.
Also, in the above-referenced system each block of the storage corresponded to a page of text. Each block had to accommodate a normal page of text. Thus, if the pages of a job were short, much unused tape storage area resulted.
In an attempt to provide denser utilization of a bulk storage, consideration has been given toward further subdividing blocks or segments into portions. Thus, if each block were segmented into eight portions and a page were allowed to start at any portion boundary, up to eight short pages could be included on a block. A much more sophisticated logging system is required than that taught in the above patents, however, because in the patents the beginning of each block denoted the beginning of a page. In the contemplated improvement of segmenting the blocks, several situations can exist. The first portion of a block may be the beginning of, or the middle of, a page. In fact, any portion on a block might begin a page, but no data is recorded along with the portion to reflect this fact.
In the contemplated system described in the preceding paragraph a system design constraint was that once a page is begun on a block it must be continued, on that block, physically, until the end of the page or the end of that block. If it was necessary to continue into another block, this was allowed without requiring a pagination break to take place. However, numerous scattered portions of blocks are opened during text revision that cannot otherwise be used for later recording because of text that exists on subsequent portions of those blocks that cannot be written over. Thus, it is evident that an efficient means to compress the stored text on the storage blocks is desirable to, thereby, condense the used storage area on the bulk storage device without requiring a condensation buffer of substantial size.
It would, therefore, be advantageous to provide a segmented bulk storage logging and controlling system and method which overcomes the above shortcomings of the prior art to provide increased utilization of the storage capability of the storage device due to improved controlling techniques.